The present invention relates to wafer management, and particularly to a system and method of coinsurance wafer management for use in MPW (Multi-Project Wafer) shuttle service that manages process scheduling of the coinsurance wafers and provides a business model that makes good use of the coinsurance wafers.
Development of IC (Integrated Circuit) fabrication technology in the semiconductor industry has lead to exponential growth in mask cost for each process. Taiwan Semiconductor Manufacturing Company (TSMC) has developed a foundry industry device prototyping service called Cyber shuttle or MPW shuttle service enabling designers to explore the benefits of leading-edge technology without committing to large volume wafer starts, and helping clients to shorten their new design development and reduce the development costs, including mask costs, during trial production and characteristic evaluation of the real chip trial stage. In addition, the MPW shuttle service dramatically reduces NRE (Non-Recurring Engineering) charges for small wafer volumes, enabling fast, low-cost prototyping.
The MPW shuttle service enables different clients to book an MPW shuttle and deliver their product design to the MPW shuttle service provider. Once all of the design information is received, each design is translated and produced on a common mask with appropriate allocation. Subsequent to IC fabrication, the MPW shuttle service provider delivers the ICs to the corresponding clients.
FIG. 1 illustrates a schematic diagram of the MPW shuttle service. In FIG. 1, a mask 110 including product designs A (111), B (112) and C (113) is commonly produced for different clients. The mask 110 is transferred to each die 101 of the wafer 100 by photolithography. Subsequent to IC fabrication, the MPW shuttle service provider delivers IC products A (120), B (130) and C (140) to the corresponding clients. The MPW shuttle service enables clients to share costs by producing a common mask for rapid processing of new products and designs to silicon-proven verification status.
In IC fabrication using one mask for one device, a number of insurance wafers are prepared as backup wafers for the original wafers that are scrapped in the process, in which the insurance wafers and the original wafers are processed with the same process. Since this type of the fabrication includes only one device on a wafer, it is clear that the insurance wafers belong to the device owner, and the insurance wafers may be provided to the device owner at no cost if the quantity of the original wafers scrapped in the process is less than that of the insurance wafers.
In another type of IC fabrication using one mask for several devices, such as the MPW shuttle service, a number of backup wafers are prepared as replacements if the original wafers are scrapped in the process. Since the wafers may be produced into different devices using a common mask and these devices belong to different device owners, the backup wafers are called “coinsurance wafers” belonging to all device owners. However, the information of the coinsurance wafers cannot be disclosed in detail or freely disclosed due to confidentiality considerations.
With the advance of IC fabrication, only a few of the coinsurance wafers become replacements due to process failure. However, since device owners cannot receive sufficient information regarding the coinsurance wafers, the MPW shuttle service provider or foundry and the device owners cannot make good use of the coinsurance wafers, resulting in scrapping of the coinsurance wafers and increased production costs. In addition, if the device owners need more wafers, they have to restart a complete wafer fabrication process, thereby increasing the cycle time of fabrication and related costs.